i think i already did it in my game, using the MW / Oblivion console command
set timescale to 20
30 should be default value, atleast it was in Oblivion. 1 should be real-time
That one doesn't persist though(does it?) and you have to set it every time you load your game.
Unfortunately I've been unable to get the old fGlobalTimeMultiplier=1.000 to work in either of the INI files.
Tried [General] in Skyrim.ini and [General]&[Main] in SkirimPrefs.ini